In a long term evolution (LTE) system, user equipment (UE) sends uplink control information (UCI) to a base station eNodeB by using a physical uplink control channel (PUCCH). The UCI includes a scheduling request indicator (SRI), a hybrid automatic repeat request-acknowledgment (HARQ-ACK), and channel state information (CSI). The SRI is used to indicate that the UE applies for an uplink resource. After receiving the indicator, the base station allocates a PUSCH resource to the UE. The HARQ-ACK is used to indicate a decoding result of downlink transmission. The CSI is used to feed back information related to downlink channel quality.
Currently, a PUCCH resource is allocated by an eNodeB to UE. The eNodeB allocates a resource index to each UE, to determine a resource that can be used by the UE. With reference to a system information block type 2 (System information block type 2, SIB2) message delivered by a cell, the resource index allocated to the UE may be specifically mapped onto a resource block (RB). If the allocated PUCCH resource is a periodic channel quality indicator (CQI) and a SRI, the eNodeB further allocates a config index to each UE, to determine which subframe and which period are used by the UE to occupy a corresponding PUCCH resource, so as to ensure that the UE and another UE are multiplexed on a same PUCCH resource and uplink bandwidth of an LTE system is shared.
Currently, in an existing resource allocation manner, an RB that is on a PUCCH resource and that is nearest to an edge of a frequency band is usually allocated first. A sequence in which the eNodeB allocates a format 2x resource can be summarized as “time division→code division→frequency division”. Specifically, after first selecting the first available resource index (cqi-PUCCH-Resource Index) on a format 2x RB near to the edge of the frequency band, the eNodeB sequentially allocates, to different UEs, all cqi-pmi-config indexes (cqi-pmi-Config Index) corresponding to the resource index, and preferentially finds out whether an appropriate timeslot resource (that is, a cqi-pmi-config index) that can be used by the UE exists on an occupied resource index. When allocating a resource to the UE, if the eNodeB finds that no appropriate timeslot resource that can be used by the UE exists on all occupied resource indexes (for example, all the cqi-pmi-config indexes corresponding to the resource index have been allocated by the eNodeB to different UEs), a new resource index should be used. Therefore, when allocating a resource to the UE, the eNodeB selects a timeslot resource on another available resource index on the RB. When the eNodeB allocates a resource to the UE, if all timeslot resources on all available resource indexes on the current format 2x RB have been allocated, the eNodeB uses a resource on a next RB. A manner of allocating a resource on the next RB is the same as a manner of allocating a resource on the previous RB.
In the foregoing solution in which an eNodeB allocates a resource to UE, regardless of a quantity of UEs in a current cell, the eNodeB starts to allocate a resource on an RB that is on a PUCCH resource and that is nearest to an edge of a frequency band. If available PUCCH resources are abundant and a small quantity of UEs exist in the current cell, multiplexing degrees of different RBs in a format 2x are uneven, and even such a case may occur: All resources in the cell allocated to UE are on the first RB (a UE multiplexing degree is high) and no UE is multiplexed on another remaining RB in a format 2x. UCI information of UE is interfered by UCI of another UE that is multiplexed on a same RB in the cell. At a same transmission time interval (TTI), a larger quantity of UEs on RBs with a same multiplexing degree indicates stronger mutual interference. In this case, intersymbol interference on an RB with a high multiplexing degree is relatively strong, demodulation performance of PUCCH format 2x information is relatively poor, CSI reliability is low, and downlink performance of an LTE system is affected.